BES900 low brew pressure

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
danehicks

#1: Post by danehicks »

Hey guys!

I bought a second-hand Breville BES900 (without really knowing anything much about espresso machines - I've quickly learnt :lol: ) and turns out it has a lot of problems getting up to pressure. Pulling shots it sits around 3-3.5 with a double wall filter. With the blind basket it gets up to 8 albeit very slowly and this is with the OPV wound as tight as it goes.

List of things I've tried:
- replaced all o-rings and fixed the multiple steam boiler leaks
- descaled machine (there's no blockages I've tested all the pipes)
- replaced OPV (thought it was just voiding too early - saw no difference with the new one)
- replaced solenoid valve - turns out the old one was working completely fine :(

My remaining theories are:
1. solenoid gasket orings are obstructing the flow (I didn't get the gasket with the new solenoid - so just have orings which fit well (although I don't have the little metal sleeves I've seen elsewhere??)
2. pressure gauge is off (and I've been using crap coffee => no crema)
3. pump is performing subpar (although I don't really understand how as the OPV is voiding consistently around 8 bars of pressure thus not letting the pump get any higher - from this I'm gathering the problem has to be in front of the OPV)

I'm really stumped as all these options seem rather unlikely to me - the only thing I can think of doing is replacing pump and modding a brass OPV onto it... but realllly it shouldn't need that (as you can probably tell I'm rather determined to make it work seeing as I've so much time on it...)

If anyone has any ideas/thoughts/questions please let me know!! :?

DaveB
Supporter ♡

#2: Post by DaveB »

Welcome to HB! This might sound (and be) too obvious, but have you verified that the machine isn't running in preinfusion mode? FWIW, It can be set for as long as 90 seconds, and 3-3.5 bar is about the pressure it would run. You can quickly confirm by holding down the 1 cup button with blind basket, or by pressing the up-down arrows at the same time to access the preinfusion settings.
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danehicks

#3: Post by danehicks » replying to DaveB »

Thanks Dave, although I've played with preinfusion settings already - the pressure barely moves off 0 in preinfusion. It lasts for ~9 seconds then you hear the pump kick in and it gets up to the measly 3-3.5

cdo

#4: Post by cdo »

Not to be a downer but it may have been better just to send it in to Breville where you would most likely get a refurbished 920 replacement instead of replacing all the parts... It could be the pump though. If you do send it in to Breville put all the stock parts back so that you have a set of new replacements for your next machine.

The OPV vents at 8 bar? I can't see two OPVs being that far out of spec theoretically you should be getting way up past 12 bars with the OPV fully screwed in.

DaveB
Supporter ♡

#5: Post by DaveB »

danehicks wrote: I'm really stumped as all these options seem rather unlikely to me - the only thing I can think of doing is replacing pump and modding a brass OPV onto it... but realllly it shouldn't need that (as you can probably tell I'm rather determined to make it work seeing as I've so much time on it...)
If you want to try a new pump, this brass-necked one is inexpensive and works; I'm guessing Amazon Ca has it is as well:

https://www.amazon.com/gp/product/B00B8 ... UTF8&psc=1
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